Hey man maybe I can help a bit. I owned a Cobra for several years and used it live on a regular basis. Throughout the time I owned it i went through several different cabs.... Mesa, Splawn, Vht, and the matching Cobra cab..... You mentioned that you have a Splawn with greenbacks ? If thats the case then you already have the best match for that amp IMO.. The Cobra cab sounded good but the Splawn sounds better. I compared them side by side both having greenbacks.
Dont waist your time or money on looking for a different cab to go with it. Im not sure if you were thinking about trying other cabs or not but I figured I would give you a heads up. I spent a lot of time and money on trying different speakers with it... I probably changed the speakers in my Splawn cab 10 times lol ....... In the end greenbacks were the best match. V30's sound ok with the Cobra and are not such a bad match but the amps EQ seems to go along with greenbacks better.
Ok so just a couple other tips... The Cobra loves medium to lower output pickups, very hot pickups sound like shit with the Cobra IMO... The reason being is that for the Cobra to sound its best the channel volume must be run above 1oclock, seriously this is the biggest key to getting good clear and not fizzy tone out of the Cobra. I like to keep the bass under 12oclock and the mids over 12oclock. This is on the Crunch channel....... I can give you a run down of settings if you need but the main thing is the channel volume, oh and if you have nothing in the loop set the loop mix at 12:00.